Several polymeric and fabric materials are used by the textile, glove and protective gear industry. Polymers such as polyurethanes, polyolefins, nitrites, polyesters, Nylon, natural and synthetic rubbers, polyvinyl or polyvinylidene chloride, nanocomposite polymers are permeable to chemical warfare agents at varying levels. While polymers such as thick butyl rubber, polytetra fluoro ethylene and polyvinylidene fluoride or chloride offer a good resistance to permeation of chemical agents, they are impermeable to moisture vapor permeation.
Therefore, protective coatings for moisture vapor breathable materials with out affecting their moisture vapor transmission rates are essential. A dynamic moisture vapor transmission rate of over 2000 gms/day/M2 is considered to be comfortable, to the wearer for example.
Examples of materials that show high moisture vapor transmission rates are microporous polytetrafluoro ethylene) microporous, nanoporous polymers, polyolefins, and certain nonporous solid film polyurethanes and polyesters. Woven synthetic fabrics by the nature of the weave are highly moisture breathable.
However, when challenged with chemical agents such as the chemical warfare agents, the materials fail to stop the permeation of the agents.
While solid films provide protection against permeation of microbes or spores, they do not repel or kill the microbe on contact.
Polyvinyl alcohol is a good barrier for several organic chemicals and gases. For example against chlorinated hydrocarbons, aromatics or similar compounds and is one of the few materials that does not swell in chlorinated solvents which are used in degreasing agents Films made with this material are water soluble. Based on the water soluble property as an advantage for disposable HAZMAT clothing, medical applications, gloves, suits etc. a few patents have been issued. U.S. Pat. Nos. 5,869,193, 5,658,977 relates to cold water insoluble, hot water soluble and/or dispersible, disposable films, fabrics and articles, and resin blends for producing the same. However, for producing products that are washable and reusable the polyvinylalcohol film needs to be crosslinked. Such films are brittle and the use of certain plasticizer compromises the barrier properties. It therefore the objective of the invention to provide a physical barrier by combination with low glass transition Tg hydrophilic polymers and polyvinylalcohol. In addition the ion-pair polyelectrolyte complexes made of polyamines, sulfonates, carboxylates from natural and synthetic origin are included in this invention.
Such as physical barrier material chiefly made of polyvinylalcohol and polyelectrolyte is protected by microporus membranes such as epTFE or polyesters or polyurethanes of thicknesses ranging from 0.2 mil to 2 mils.
The adhesion of the polyvinyl alcohol polyelectrolyte layer is enhanced by adhesion promoters or plasma modification of the substrate.
The author of this patent has discovered that certain highly hydrolyzed cross-linked polyvinyl alcohol films, provides moisture vapor permeation and are excellent barriers for chemical warfare agents such as mustard (blister), nerve and certain other agents. Due to the brittle nature of the polyvinyl alcohol film and its sensitivity to moisture, the film has to be encapsulated in another polymeric layer. This could be a moisture vapor permeable microporus support such as epTFE or other moisture impermeable polymers such as polypropylene, polyurethanes or polyethylene.
It was also found that blends of polyethylenemine (PEI) and the like such as PEI based nanosize dendrimers with hydroxyl or carboxyl periphery and polyvinyl sulfonate to Polyvinyl alcohol enhance the moisture vapor permeation by several folds. The use of cross linker such as organo zirconates or organo titanates (Tyzor, Dupont), dialdehydes, and epichlorhydrin type products such as Polycup (Hercules). The crosslinkers help the insolubilization as well as adhesion promotion.
This invention also provides unique compositions and method for achieving a slow release microbicidal and sporicidal composites, that is highly moisture breathable (>2000 gms/day/m2Active biocidal and catalytic composition. Addition of biocidal additives and catalytic compounds, referred to as active chemical composition in this application, may reactively deactivate certain chemical warfare agents and create a biocidal barrier. Such compositions could be blended in a liquid formulation or extruded after compounding with resins.